We will continue the isolation, purification and characterization of enzymes catalyzing the biosynthesis of saturated and unsaturated fatty acids and of cholesterol. The source material of these studies will be both animal tissues (liver and brain) and microorganisms. The special aim of these investigations is to eluide the regulatory mechanisms which control the rates and specificity patterns of lipid biosynthesis. Such information may contribute to an understanding of the metabolic derangements underlying arterial disease.